RESEARCH ARTICLE The Effect of Coronal Pre-flaring and Type of Root Canal Irrigation on Working Length Accuracy Using Electronic Apex Locators [version 2; peer review: 2 approved with reservations] Previously titled: The effect of coronal pre-flaring and root canal irrigant on apex locators’ accuracy: an in-vitro study Shimaa Rifaat 1 , Abdullah Aljami 2 , Turki Alshehri 2 , Shahad T. Alameer 2 , Alhanoof Aldossary 2 , Wejdan Almutairi 2 , Mulham N. Almaliki 2 , Faraz A. Farooqi 3 , Noha Taymour 4 1 Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, P.O Box 1982, Dammam, 31411, Saudi Arabia 2 College of Dentistry, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam, 31411, Saudi Arabia 3 Department of Dental Education, College of Dentistry, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam, 31411, Saudi Arabia 4 Department of Substitutive Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam, 31411, Saudi Arabia First published: 23 May 2023, 12:533 https://doi.org/10.12688/f1000research.133288.1 Latest published: 04 Sep 2023, 12:533 https://doi.org/10.12688/f1000research.133288.2 v2 Abstract Background: Successful root canal treatment is influenced by the apical extent of root canal preparation and the eventual root canal filling. Achieving the full working length until the apical constriction, which is usually 0.5 – 1 mm shorter than the anatomical apex, is crucial. Electronic apex locators were used to detect the working length more accurately. There are six generations of electronic apex locators in the market. The selection of the appropriate irrigation with each apex locator for accurate working length determination is not fully investigated. Methods: The actual working lengths of 120 freshly extracted human single-rooted teeth were measured and compared with their working lengths using 3 rd generation (Root ZX) followed by 6 th generation (Raypex 6) apex locators in dry medium, presence of 5.25% sodium hypochlorite, and 2% chlorhexidine, without coronal pre-flaring and after coronal pre-flaring using the same irrigating media. Data were collected, tabulated, and afterward analyzed using one-way ANOVA with post-hoc to evaluate the significant difference in average working Open Peer Review Approval Status 1 2 version 2 (revision) 04 Sep 2023 version 1 23 May 2023 view view Amira Salem , University of Otago, Dunedin, New Zealand 1. Rania El Backly , Alexandria University, Alexandria, Egypt 2. Any reports and responses or comments on the article can be found at the end of the article. Page 1 of 29 F1000Research 2023, 12:533 Last updated: 04 SEP 2023